In recent years, there is a demand particularly for flat-panel-type three-dimensional picture display devices that do not require special glasses. In one type of such three-dimensional picture display devices, a light beam control unit is disposed facing a display panel (display unit) such as a direct-view-type liquid crystal display unit or a projection-type liquid crystal display, and the light beam from the display unit is controlled to be directed toward the observer.
The light beam control unit has a function by which, regarding a particular position on the light beam control unit, pictures appear corresponding to the angle of observation. Regarding a case in which only the left-right parallax (the horizontal parallax) is applied, a specific example is a structure in which linear light beam control elements such as slits (parallax barrier) or cylindrical lenses are disposed in the horizontal direction on a periodic basis. As a representative structure, a barrier or a lenticular sheet is known. In each pixel of the display unit is displayed the color and brightness information (parallax information) corresponding to the direction that is observed via the light beam control elements, and a collection of parallax images corresponding to a single aperture area is called an element image. Herein, the expression can be any one of the following: the observer views pictures corresponding to the observation position via the aperture area; and the light beams emitted via the light beam control elements constitute three-dimensional images.
The techniques of combining a display unit and a light beam control unit are categorized into binocular display, multi-view display, super multi-view display (super multi-view condition of multi-view display), and integral imaging (hereinafter, referred to as “II”) depending on the parallax count (where parallax is the difference in vision due to viewing from a different direction) and depending on the design guideline. In binocular display, stereoscopic viewing is achieved by applying binocular parallax with two parallax images. In contrast, in other techniques, kinematic parallax is applied in varying degrees. Thus, such a picture is called “three-dimensional picture” in distinction from “stereoscopic picture” achieved in binocular display. The abovementioned method of observing parallax images through the light beam control elements has essentially the same fundamental principle as the principle of integral photography (IP) that is a known technology.
Of the techniques described above, for example, the II technique has a feature that the viewpoint position can have an enhanced degree of freedom by increasing the parallax count; and stereoscopic viewing can be performed over a relatively wide range (wide visible area). The parallax count can be increased according to the pixel count of pixels constituting an element image. However, since there is an upper limit to the resolution of the display unit, the interval between the light beam control elements grows larger. That leads to deterioration in the resolution of the three-dimensional pictures.
In order to suppress the deterioration in the resolution of the three-dimensional pictures, a one-dimensional direct-view-type unaided-eye three-dimensional display device is known in which the direction of presenting the parallaxes is limited to the horizontal direction, and the parallaxes are not presented in the vertical direction (up-down direction). However, in a one-dimensional direct-view-type unaided-eye three-dimensional display device, there remain known issues such as deterioration in the resolution in only the horizontal direction or occurrence of moire due to the optical interference between the periodic structure of the light beam control elements and the periodic structure of the pixels (aperture areas and light interception areas) that are arranged in a matrix in the display unit. Typically, with the aim of improving the resolution balance or with the aim of removing the moire in an effective manner, a technique is known for tilting the light beam control elements.
Meanwhile, in a one-dimensional direct-view-type unaided-eye three-dimensional display device, the image quality deteriorates depending on the arrays of colors (color arrays) observed through the light beam control elements. For example, in the case of color arrays in which same colors are arranged in the horizontal direction, stripes of same colors appear thereby leading to deterioration in the image quality.